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Analysis of Collimation of Astigmatic Diode Laser Beam by Objective Lens
Laser Systems > Beam Delivery
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Task/System Illustration
high NAlaser diode
quality of beam collimation = ?
dot diagram wavefront
error
phase view
beam parameters
collimating objective lens
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Highlights
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• laser diode modeling including astigmatism
• various options for evaluation of beam collimation influence of astigmatism
• quality analysis of beam truncated by lens aperture
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Parameter Description / Value & Unittype/number single mode IR diode laser from Laser
Components: WSLD-1064-050m-1-PDcoherence/mode single Hermite Gaussian (0,0) modewavelength 1064 nmpolarization linear in y-direction (90°)FWHM of beam divergence with astigmatism
20° × 10° (i.e. 16.97° × 8.49° referring to the 1/e2
waist radius), astigmatic shift set to 11.6 µminitial M2 in x- and y-direction 1.00 × 1.00
Specification: Light Source
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high NAlaser diode
high NAlaser diode
Specification: Collimating Lens
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Parameter Value & Unittypes of lens surfaces 3 lenses with 6 spherical surfacesnumerical aperture (NA) 0.63materials M1: N-SF6*
M2,M3: N-BK7** from catalog "Schott_2014"
M3M2M1
a
high NAlaser diode
Specification: Detectors
Position Modeling Technique Detector/Analyzerfull system 3D system ray tracing general overview of light behavior in systema ray tracing phase aberrations (RMS of wavefront error)a ray tracing ray directions from dot diagrama field tracing intensity distributiona field tracing beam parameters (for x × y):
• full 1/e2 angle divergence• M2 value
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high NAlaser diode
Results: 3D System Ray Tracing
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Collimation Investigationvia Ray Illustration
high NAlaser diode
Results: Wavefront Error without Astigmatism
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Collimation Investigationvia Wavefront Error
RMS = 0.03 λ
Results: Wavefront Error with Astigmatism
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Collimation Investigationvia Wavefront Error
Astigmatism of source causes asymmetric & stronger wavefront error.
RMS = 0.70 λ
high NAlaser diode
Results: Ray Directions without Astigmatism
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Collimation Investigationvia Ray Directions
The x- and y-componentof the direction vectorof every ray are almost zero.
0.0004
0.0004
high NAlaser diode
Results: Ray Directions with Astigmatism
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Collimation Investigationvia Ray Directions
The x- and y-componentof the direction vectorof every ray are still negligible.
Astigmatism of source causes asymmetric distribution of directions.
0.003
0.0005
high NAlaser diode
Result: Field Evaluation without Astigmatism
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Collimation Investigationvia Beam Parameters
Parameter Value & Unitfull 1/e2 divergence angle 0.02° × 0.04°M2 value 1.09 × 1.01
Simulation Time ~4 s
intensity
high NAlaser diode
Result: Field Evaluation with Astigmatism
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Collimation Investigationvia Beam Parameters
Astigmatism of source causes changes of• divergence angle• beam quality
Parameter Value & Unitfull 1/e2 divergence angle 0.02° × 0.05°M2 value 1.06 × 1.01
Simulation Time ~4 s
intensity
high NAlaser diode
Document & Technical Info
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code BD.0001version of document 1.0
title Analysis of Collimation of Astigmatic Diode Laser Beam by Objective Lens
category Laser Systems > Beam Delivery (BD)author Hartwig Crailsheim (LightTrans)used VL version 7.0.0.29
Specifications of PC Used for SimulationProcessor i7-4910MQ (4 CPU cores)RAM 32 GBOperating System Windows 10
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